Cellulases are enzymes which were considered to act only in a neutral or acid range but not in an alkaline laundry detergent solution. Finding of an alkaline cellulase derived from alkaliphilic microorganisms belonging to Bacillus sp. by Horikoshi (refer to Japanese Patent Publication No. Sho 50-28515 and Horikoshi & Akiba, Alkalophilic Microorganisms, Springer, Berlin, 1982) enabled its use for laundry heavy-duty detergents. Since then, alkaline cellulases produced by alkaliphilic microorganisms belonging to Bacillus sp. have been developed (refer to Japanese Patent Publication No. Sho 60-23158, Japanese Patent Publication No. Hei 6-030578 and U.S. Pat. No. 4,945,053) and are now incorporated in laundry detergents.
Recent progress in genetic engineering has enabled mass production of enzymes for detergents, which also applies to the production of alkaline cellulases. A number of genes for alkaline cellulases have already been cloned, their nucleotide sequences have been determined. Furthermore, technique for mutagenesis and breeding of the enzyme-producing bacteria or mutagenesis of a gene encoding the enzyme has been introduced.
Productivity of them on an industrial scale however does not reach a satisfactory level, and there is a demand for alkaline cellulases which can be produced efficiently.
An object of the present invention is therefore to provide an alkaline cellulase which acts favorably in an alkaline region, and can be mass produced readily because of having high secretion capacity or having enhanced specific activity.